Centrifugal pump



Dec. 8, 1953 c. A. SCHELLENS 2,661,698

\ CENTRIFUGAL PUMP Filed March 21, 1951 2 Sheets-Sheet l Dec. 8, 1953 c.A. SCHELLENS 2,661,598

CENTRIFUGAL PUMP Filed March 21, 1951 2 Sheets-Sheet 2 Patented Dec. 8,1953 UNITED STATES PATENT OFFICE 12 Claims.

This invention relates to centrifugal pumps and more particularly tosingle stage centrifugal pumps employing one double inlet runner, such apump being shown in my Patent No. 2,101,653, granted December 7, 1937.In order to provide for assembling such apparatus it is customary todivide the pump housing into two parts on a horizontal plane whichcontains the axis of the driving shaft of the runner, the two partsbeing secured together by bolts. It has been found diflicult to make thejoint between the parts tight against leakage, particularly when highpressures are developed and when diffuser vanes are employed.

In high pressure pumps it is necessary that the clearance between runnerinlets and the stationary wearing rings be made as small as possible tominimize leakage of pressurized liquid from the chamber containing thedischarge portion of the runner to the suction chamber at the inlets ofthe runner. To this end, the bearings of the shaft on which the runneris mounted must be accurately centered with respect to the wearingrings, and it is extremely difiicult to 'securethis centering'with thesplit casing construction. An object of this invention is to providestructure for assembling anddisassembling the separable parts of thepump without disturbing the pipe joints which are secured to the casingto supply liquid to the pump suction and to conduct away the liquiddischarged by the pump. For this purpose, the pump casing is made with acircular opening at one side which is concentric with the drive shaftand is of sufficient size to admit the removable parts which must beassembled within the casing to complete the pump. In assembling thepump, these parts are moved into the casing along the axis of the driveshaft, as hereinafter described, and a plate or head is secured to thecasing to close the opening.

Another object of the invention is to provide a novel means for securingin place two diaphragms which are mounted with a diffuser within thecasing to enclose the discharge portion of the runner or impeller insuch a manner asto avoid or minimize leakage of pressurized liquid fromthe discharge end of the diffuser through the joints between thediaphragms and the casing. V

.,For a more complete understanding of the "invention, reference may behad to the following description thereof and to the drawing, of whichvFigure 1 isa sectional view of a single stage "centrifugal pumpembodying the invention;

Figure 2 is a section on the line 22 of Figure 1, on a larger scale;

Figure 3 is an enlarged sectional view of a part'of the structure shownin Figure 1;

Figure 4 is a sectional view of a modified form of the invention shownin Figure 3; and

Figure 5 is a section on the line 55 of Figure 4.

The pump illustrated in Figure 1 comprises a casing l0 which isdetachably secured to a main casing [2 by suitable means such as bolts[4. The main casing l2 may contain a prime mover (not shown) 'for thedriving shaft l6 which projects through the casing II]. The pump casingshown on the drawing consists of three parts, namely, an outer casingmember 20, an outboard head 22 and an inboard head 24. 'These threeparts enclose a suction chamber 26 which communicates with the inlets ofthe runner or impeller 30 hereinafter described. The heads 22 and 24close the circular openings in the casing member 20 which are concentricwith the axis of the shaft IS, the opening which is closed by theoutboard head 22 being of larger size than the diameter of the inboardhead 24 and also of all of the other parts, hereinafter described, whichmust be inserted to assemble the complete pump. The head 22 contains asuitable ball bearing assembly 32 for the end of the shaft l6, thisbearing being mounted in a suitable retainer or holder 33 having a cover34 which protects the end of the shaft. The bearing 32 may serve as asteady bearing and as a thrust bearing for axially positioning the shaftand the rotating members relatively to the casing. A roller bearing 35is provided for the portion of the shaft between the head 24 and themain casing I2. This bearing is mounted in a retainer or holder 36 whichis secured to the casing l2 and is supplied with a cover 31 which clampsthe outer race of the roller bearing 35. The heads 22 and 24 areprovided with suitable soft packing 38 and 40 to prevent leakage fromthe suction chamber 26 along the shaft. The shaft has a splined portion42 on which is slidably fitted the hub 44 of the impeller 36, theimpeller being held in proper axial position on the shaft [6 by spacingelements on the shaft, including sleeves 45-and 46, which are grippedlongitudinally between a nut 41 onthe outboard end of the shaft and ashoulder 48 on the shaft abutted by the inner race of the roller bearing35.

Integral with the casing member 20 is a shell 50 which encircles theshaft and impellerand contains a volute discharge duct 52 to receivepressurized liquid from the impellein This duct communicates with adischarge pipe (not shown 3 which may be secured to a flange 54 on theeasing member 20. Similarly a supply pipe (not shown) may be secured toa flange 56 on the casing member 20 so as to communicate with thesuction inlet 58 of the pump casing. The shell 50 of the casing member20 has a stepped bore therethrough which is coaxial with the shaft IS,the steps. forming shoulders 60; and Slwhiclrface towarditheoutboardside'of the casing. Mounted within this bore are two diaphragmsB4 and 66,

the outboard diaphragm 64 having a marginal p' area on its outer face oron a radial flange, 6,8, l.

which bears on the shoulder 60, the inboard 'diaphragm 66 having amarginalraiea on a radial flange 70' which bears on the shoulder 6 2Gripped between the periphralportions of-the diaphragms is a diffuserwhich encircles-the dis charge ports 14 of the impeller and ispreferably composed 2 of two separable annular parts 'lz and T4: thelatter having a series ofQVa'nes TBQeXt ding. therefrom. to abut: the,part 1;. Their difii s r rid Passes ro h w a s e 84 h eh enemas;arb'undlth'ej 'di-fiiiser and communicates with the voluteduct .52. Theliquid pressurejn th'fpassage, 841s much higher than in the sue.- tiorIchamber. 26[ Hence it is necessary that the joints between theoasin'g'memberwill and the diaphragms 64 and Blifbe. tight. Whenthepurnp ,is lopfatin'g, the pressure of the liquid in the clfiamixerv l1 s and theclearance 833 between the diffused and they inboard diaph'ragm B5coperates withsl ficient force to: maintain. ,a. tight seal at th pointthe fliduid pressure in} the dis;- ch Q passage 8 4 which, communicateswith a clearance '88 between the difiuseii and the, outl e TdadiapH einMe s db h h fianee 6.8

way from, thejshoulder' Q and thus to promote lea ag at 'thatpointt Inorder to ov r omcih means offrafscrew thread or equivalent in theeffectsfof such liquid'pressure l mount a ringfly outb a n portionbfythe b e. ofthe casin member- .59 QaSQiiidicated at 192. The clearance.diameterofthis portion of the .bQreis sufiiqiently large to admit the:diaphragms ,and. .thedifiuser sac that t ey c n be inserted and asse biq m the bore whenintroducedthrough theside open: v. pe mg ing normallyclosed by 'the head 22.

01i mi e t a e s .e q twn i rm s aeed r und desi edwe th e 9 9 e nadapted .to receiveca series oi bolts 9.;whi ch e ce tendvthrough thering in the direction parallel to, the shaft is} After the diaphragm;and, dif serv ndim el er hav e ng sseliip das in i cated in Figure l,the ring is screwed into -p oe until it abuts the outboarddiaphragn fit;It then be slightly zbacl zedj off, whereupon-the indii d1 a bol sflp rst in tQPE S-S IQQWeg i the .ou bo d ianh a m wa t q lisi e ss :fifitheceq ier-a ains heshoelde fl th urin atishtioiptifvt iezne ztshavebeeaeifitted.

dif -us r also. 7 as a, flan e. 1 l 2 .a ts. oute p 1 e1 .htl1a ne a siular enin thstandi- In operating high speed pumps it is necessary tomake frequent inspections of the bearings and to renew them whennecessary. Such inspections are facilitated by the fact that thediameters of the removable parts shown in Figure l are less than thoseof the openings through which they must pass to be assembled ordisassembled, -'I;-hus theroller bearing 48; and its retainer 3E. andeover-3e1 can pass through the opening normally closed by the inboardhead 24. The inboard head likewise can pass through the bore irrtheshell 50 when the diaphragms and diffuser have been removed, and allthese parts, aswell asthering 90, can pass through the outboard openingin the casing l0. Furthermore, since the reller bearing 48 is mounted ina retainer, any scoring of the mounting due to accidentalseizure will beconfined to the retainer wh ch. an easil e e laced he. mai cas rsmaie smta t i I s de i ble hat, h an Q i lie in: a d i m, e. firmly el nst. te shoulder BZl seas to, avoid leakage whether or not t e pum s de l in ru l s u eo this e d he fi s r rt v r a e w th la es i h P 793 s n pposii ec ons e 7 a t "has afiange 95 at its inner perimetehthis ange bearinga t. th adieeent id oi th ou board, d a hr m 9; T e difiuser. a saflan e12 uter, 1 E 38?? earin against the. nb a d dia hra m 61 nce we? flangesare radially offset; the thrust of the out oard, aphra m inst heflsneflfi; ,wh h ansm t d h ough, he nes 5 and the l e e 98 to the,diaphragm 66 tends to distort the ser b spr n in rt rna ts l ght a isdis- 9 7 9 03 P TQV G p i fifi hi ss e diaphragm fiange'lfl against theshoulder :62 the imensi O he d us rt and he r' an being such as toresult in such distortion of the difiuser when the, outboard diaphragmis clamped strongly against the shoulder 50':

In the case of veryhigh delivery pressures, a difiuser structuresuchasis shown in- Figures 4 and' 5 may, be preferred, In this caset'hefi ser, Par ".9 and are r v ded with fla ge 1 $4 a d. e j-res t v atthat meet er met heo ens 16' sceur t csfiai d to have, a radial forcefit against -the' shoulder 0 t diap r B6 q Pr e i area while h eetaseetwsen the flan e 194 an e. a hra m 5. ,me nts by. th iehtez a abutment.t een themhe a t flz qithe imam: hea ngegai is .th 'r aee i th dia hrar. 5 is aneelisnrovidced th.a. er btlraldialysl ts. I HQ e qalize theliquid nressure i ths=. 1ee tae9e .r e ween the part 1 H12 and ineiaphragm 66 withthe pressure in the passage -1, in e heinressuse wi in eh rffusers at al mim lesst n n-- herna ea e athemv Qr -inthe ex e nal dl aran soo e e iftuse pa ts. it g iqlrt e p ssa e 7 8 twi e:unisa esthef c Parts of ho ifi se retie bl -slamped agate bx n at s l uid pr ssuand me de igfnia ea the ifiuser arts. du to axia a e aute afianeeslfland l i iec rthet ees sary tight contact at 62.

I claim;

a r ent ii eai numbaareasi s includ n threaded outboard portion and aninboard por:

tign, i sma lsn vi ti lr ,t ts m n. the router ni mie he l,.de,betwen-.s idm t a cular diaphragm" closing said opening," saiddiaphragm having a marginal area fitting against ;said shoulder to forma joint normally washed by liquid pressurized by said pump, and means a,for pressing said area strongly against said shoulder to make the jointtight, said means consisting of a ring screw threaded in the outboardportion of said opening to abut the outer side .of said diaphragm, theclear diameter of the .threaded portion of the opening being greaterthan the diameter of the diaphragm, and a series of bolts threadedthrough said ring parallel to the axis thereof to bear against the outerside of said diaphragm, said bolts being, uniformly spaced around thecircumference of said ring.

2. In a centrifugal pump, a casing including .-,.a member having acircular opening with two annular shoulders therein, the inboardshoulder being of lesser diameter than the outboard shoulder, twocircular diaphragms in said opening bearing against said shouldersrespectively to formjoints washed by liquid pressurized by said pump, astifily resilient deformable member betweensaid diaphragms engaging theopposing faces of the diaphragms near the perimeter thereof, and meansfor pressing said diaphragms strongly against the respective shouldersto make said joints tight, said means consisting of a ring 1 outboarddiaphragm is pressed strongly against its shoulder by said bolts, themember is deformed to press the' inboard diaphragm against its shoulder.

Apparatus of the class described comprising amain casing, a pump casingsecured thereto, said pump casing having an opening in the outboard sidethereof remote from said main casing, a head secured to said pump casingto close said opening, a shaft projecting from said main casing throughsaid pump casing, an end of said shaft being journalled in said head, adoubleinlet impeller keyed on said shaft, said pump casing and headenclosing a suction chamber communicating with both inlets of saidimpeller, said pump casing having an inner portion enclosing a volutedischarge duct and having a stepped bore coaxial with said shaft, twodiaphragms mounted within said bore and pressing against the stepstherein, a diffuser gripped by the said diaphragms in said bore andencircling the discharge ports of the impeller, and means for pressingsaid diaphragms against said steps, the opening in the outboard side ofthe pump casing being of larger diameter than the impeller, diffuser,diaphragms, and pressing means whereby said impeller, diffuser,diaphragms and pressing means can be introduced through said openingalong the shaft to assemble the pump structure.

4. Apparatus as in claim 3, said pressing means consisting of a ringremovably mounted in said bore next to the outboard diaphragm, and aseries of bolts threaded through said ring parallel to the axis thereofand bearing against said outboard diaphragm, the portion of said bore inwhich the ring is mounted having a clear diameter greater than that ofthe diaphragms, diffuser and impeller.

.. V 5. Apparatusas in claim 3, said pump casing having an opening onits inboard side concentric with the shaft, an inboard head closing saidopening, said inboard head being of smaller diameter than the outboardopening, whereby it can be introduced. into said casing throughsaidoutboard O ening.

said shaft, an impeller keyed to said shaft within said inner shell, twospaced diaphragms fitted within saidinner shell and enclosing a chamberwithin which said impeller is rotatable, said inner shell having astepped borewithin which saiddiaphragms are mounted and annularshoulders within the bore against which the diaphragms are pressed, adiffuser gripped between the peripheral portions of the diaphragms, and

means holding the difiuser and diaphragms, in

assembled relation, said means consisting of a ring threaded into aportion of said bore to abut, one of said diaphragmsan-d .a plurality ofbolts. threaded through said 'ring and parallel to the shaft, axis topressathe. adjacent diaphragm.

against one of said shoulders and against, said.

I diffuser.

7. A centrifugal pumpcomprising a casing a.

shaft extendingtherethrough and an impeller:

keyed on the shaftysaid casing consisting of am outer shell memberhaving two opposed openings concentric with the shaft, two suction headssecured to said member to close said openings andi enclose with saidmember a suction chamber, each said head having a bearing for saidshaft, an inner shell within andintegral with the outer shell member,said inner shell enclosing a volute discharge duct and having a steppedbore concentric with said shaft, two diaphragms mounted in said bore andspaced to form a chamber in which said impeller is rotatable, a diffusergripped between said diaphragms and encircling said impeller, saiddiaphragms having annular shoulders bearing against steps in said bore,and means for holding the diaphragms and diffuser in assembled relation,said means consisting of a ring screw-threaded into said bore to abutone of said diaphragms, and a plurality of bolts threaded through saidring parallel to the shaft axis to bear against the adjacent diaphragmat spaced points.

8. In a centrifugal pump having a casing, a shaft extending through thecasing and an impeller keyed to the shaft, said casing having a steppedbore coaxial with the shaft and of larger diameter than the impeller,two diaphragms mounted in said bore and spaced to form a chamber inwhich said impeller is rotatable, said diaphragms having eripheralshoulders bearing against steps in said bore, a diffuser gripped betweenthe peripheral portions of said diaphragms, said diffuser consisting oftwo separable annular parts with vanes between, said vanes beingattached to one part and bearing against theother, a flange on the innerperiphery of one said part bearing against the adjacent diaphragm, aflange on the outer periphery of the other said part

